In a surprising find, researchers in Finland have discovered that men who've been infected with the sexually transmitted disease chlamydia appear to have a reduced risk of developing prostate cancer, Reuters Health reports. Scientists at the National Public Health Institute in Oulu expected to see an increased risk for the cancer, based on previous studies showing that chlamydia boosts a woman's risk for cervical cancer. But a study of male blood samples taken over a 30-year period showed that men who had antibodies against chlamydia, indicating a previous infection, had a 31% lower incidence of prostate cancer than men who had never been infected with the STD.

Even more unexpected was that the researchers determined that the higher the number of chlamydia antibodies in the blood, which indicate a persistent infection or multiple infections, the lower the cancer risk was. The researchers say their findings should not lead men to attempt to become infected with chlamydia to lower their cancer risk, but they note that it does open the door to antibody research for possible cancer risk-lowering treatments.